Stringed musical instrument



Aug. 23, 1949. J. w. M BRIDE STRINGED MUSICAL INSTRUMENT 5 Sheets-Sheet 1 Filed May 29, 1945 R: Y 0M M m m c Job/7 Aug. 23, 1949. J. w. MCBRIDE 2,479,757

STRINCED MUSICAL INSTRUMENT Filed May 29, 1943 5 Sheets-Sheet 2 M6 INVENTOR Y M5 Jab/7 .Mc5/v'0e ATTORNEY Aug. 23, 1949. J. w. MCBRIDE 2,479,757

STRINGED MUS ICAL INSTRUMENT Filed May 29, 1943 5 Sheets-Sheet I5 INVENTOR dob/7 M/McBr/de BY 7M ATTORN EY Aug. 23, 1949. J. w. M BRIDE STRINGED MUSICAL INSTRUMENT 5 Sheets-Sheet 4 Filed May 29, 1943 l NVENTOR John 14 BY ya 5/702? TTORNEY 1949. J. w. M BRIDE 2,479,757

STRINGED MUSICAL INSTRUMENT Filed May 29, 1943 5 Sheets-Sheet 5 Fi/f'er INVENTOR ATTORNEY Patented Aug. 23, 1949 UNITED STATES PATENT OFFICE 1 S-TRINGEDMUSICAL INSTRUMENT Jonn w. McBride, nurbannoana Application May 29, 1943, SeriaPNo. 489,040

1-0 Claims. 1

This invention relates toa. musical instrument; and, more particularly, to an. instrument. utilizing tensioned strings.

The pitch of the musical sounds produced by vibration. of the strings. can be. determinedby-adjusting the free vibrating. lengths of the strings. This can be accomplished in. anumber of ways: for. example, as by the aid. of mechanism illustrated in. a patent issued. on. April 20, 1943, to John W. McBride; and having number 2,316,799. This: mechanism includesa rotatable rod having an axis substantially paral-leito the string and carrying a helicab-likecrest. The angular position of the rod determines'which point. ofthe crest contacts the string and, thereby, the free. vibrating length.

It is one of-the. objects of this invention. to improve in; generalithe controlmecha-nism. for such. rotatable. rod mechanisms for: determining the free lengths. of vibration.

The strings in such instruments are usually stretched betweentwo fixed-points or bridges. Accordingly, stopping of the. string at. any intermediate point defines two lengths, respectively between the point of contact and the bridges. :It is another object of this invention. to: co-ordinate these two lengths thus determined, sothateither' of. them, or both, may be used, as desired. In order tofacilitatesuch operation; the. strings are longer than. those that;- have been. usually provided..

It. istherefore still. another object of. this; iii-- vention to provide an instrument: having relatively long. strings, each capable of operation to provide. a pair of usable-free vibrating lengths.

Itisstill another objectof this invention to provide a readilyrmanipulable string; damping device that can. be used to stop. string vibrations.

This invention possesses many other advan tages, and has other objects which maybe: made more easily apparent from. a consideration'ofv one embodiment of thein-vention. For this-purpose there is shown a form in the drawings accompanying and forming part ofthe PIBSGHil-SPBCi'fiication. The form willnow be describedfin. detail,-v illustrating the' general principles of the inven-. tion; but it is to' beunderstood that this detailed. description is not to be taken in. a. limit-- ing. sense, since the scope of this invention. is best defined by theaappended claims.

Referring to the drawings;

Figure 1 isa' topplan view of: aninstrument incorporating-the. invention;

Fig. .2: isa side; elevation; Eartly: insectionytaken; a1ong .plane;2 -2. oi-.-F.i.j1;

Fig.;.-3-is antenlarged. fragmentary plan. view, partly'in section, otathat portion of the instrument. which provides the control of the free vibrating-qlengths-of the strings;

Figs-=4. isasectional view, taken along plane 4-4 of Fig. 3;

.-1=.-ig. :5 :is a-sectionalview, taken.- along plane 5-.-&-.ofFig;;-3;.

. Fig. 6' is. a; sectional. view;.- taken: along 7 plane 6-Brcf"Fig'.4;

Fi'gg'l is a, fragmentary sectional view, taken along plane.'|---| .-of-.-1Eig. .1',,.a. part of the section being-"broken .away toreduce-the-size of the figure;

Fig. 8 isan enlarged sectional view, taken. along plane chitin-2;.

Fig.- 9. isa. fragmentary bottom. plan view,.taken in the direction at thearrow: 9 of Fig. 2;.

Fig, l0 issa. sectiorlalview-ntaken along plane l-D-l-ll. of Fig". 3;;

Figs llisa fragmentary sectionalview, taken along. planel ll.| of i0;

.E'ig. .12..is.:an enlarged: sectional view, taken along,.p1a.me=i.2.-l2 of. Fig. 6;; and

Fig. 1-3..isa wiring diagram, illustrating the manner in..wh-ieh-..the-electric pick-ups for the vibratingstrings. may .be. controlled for. tone and volume.

The. .operating parts of .the instrument are supported...upon abod-y. l. that-may be fashioned 0t wood,,or.similar.material-. Thebody l isshown as.providedwith.appropriatercavities for the accommodation of. parts-oi. theinstrument, as will appear. hereinafter...

.Stringstructures-Z,3,..4; and i. (Figs. 1, 3, 5, and; 8 are. disposed in substantially parallel relation. over thetop-of the. body 1'. Although singlestringsare.shownior-each oi the string structures,. it. is, of. course. possible-to.- utilize. multiple strings. for anyofl them.

Provisions.- are made. for. tensioning. each. of the strings along the length .ofthe body. At the. righthandendnf thebod-y. I: (Figs. land 2) there is.shown:a.bridge -6.. Thisabnidge. is provided with grooves.1--in.-whicheare disposed. the-string structures12,.-3-,s4, and 5.. Thezbridgezfi may be appropriately. fastened into. a. transverse. groove formed in thesbody- I The: stringsthen :extend toward the-r right and downwardly ithroughi aperturesformedin thebedy l-, ,into the enlarged cross slot. 8. Knots 9, or othenenlargements, carried by the ends.- of thestrings,-. servetoranchon the right-hand endsa'ofthestrings inthezslotlla:

- At the-lent. hand. enmof. theinstrument of; the body lgabridse -isspmviiiedpconstructed and supported similarly to bridge 6. All of the strings 2, 3, 4, and '5 extend over the bridge 10. Accordingly, the bridges 6 and I form spaced points between which the strings may be tensioned.

For applying tension to the strings, pins I l are provided upon which the strings are wound. Pins l are arranged to be rotated in any conventional manner for adjusting the tension of the strings, as by the aid of the pegs I2.

Provisions are made for stopping each of the strings 2, 3, 4, and 5 along the length of any string. For this purpose, use is made of a plurality of rotatable rods l3, l4, l5, and I6, disposed in a longitudinal cavity 23. These rods are similar to those illustrated and described in the prior patent hereinbefore referred to. They each carry a helical-like crest Il, I8, l9, or 29 (Figs. 3 and 5). In the present instance, all of the rods re shown as hollow; in this way, excessive weight is avoided when metal is used for the rods. These rods, furthermore, may be rotatably supported at their right hand ends by the aid of integrally formed stub shafts 2| (Fig. 2). These stub shafts are accommodatedwithin bearing apertures in the bracket 22, carried by" the upper surface of the body I. The left hand ends of the rods [3, l4, I5, and I6 are rotatably supported by the aid of structure most clearly illustrated in Figs. 3 and 4. Thus, each of the hollow rods is provided with a hollow tubular extension 24, 25, 26, or 21. Within these tubularextensions project the hollow tubular shafts, such as 28, upon which the extension 25 is journalled, Shaft 28 is supported in a wall 29, shown as extending upwardly from a plate 30. The plate 30 is disposed in the recess 23 of the body! and underneath the extensions 24, 25, 26, and 21. Each of the hollow shafts may be provided with the heads 3|, 32, 33, and 34, which abut the left hand side of the wall 29.- They are held fixed in position by the aid of the set screws 35. Thrust collars, such as 60, may, if desired, be provided between the left hand ends of each of the extensions 24, 25, 26, and 21, and the wall 29.

' The heads 3|, 32, 33, and 34 are provided for "f facilitating angular adjustment of the shafts associated with them, for a purpose that will be described hereinafter. For facilitating such angular adjustment, each of the heads may be provided with a series of angularly spaced slots 33 for the accommodation of a screw driver blade, or the like. The end of the blade may be conveniently inserted inan available slot 36 for exerting a thrust to produce a rotary torque on the head. The wall 29 is arranged at an intermediate portion of the strings 2, 3, 4, and '5; accordingly, the crests l1, l8, l9, and of the rotatable rods l3, l4, l5, and I6 extend from about the central portion of each string toward the right hand ends thereof. By angular adjustment of these rods, the helical-like crests are caused to stop the string at any point along the lengths of the crest. In this way, there are two effective vibrating lengths for each string: one defined between the left hand bridge i6 and thepoint of contact of the crest; and the other defined between the right hand bridge 6 and the point of contact of the crest. The strings 2, 3, 4, and 5 are purposely made long enough so that these two sections of the strings may be vibrated by the player, either in unison or separately, as he may choose.

In this manner it'is possible to obtain varia--' tions of string length from a minmum as little as desired to a maximum which corresponds, substantially, to the entire length of a string'tbe- '4 tween the bridges 6 and III. The limits of string length occur when the helical-like crest contacts the corresponding string at the extreme right hand part of the crest. The minimum length then corresponds to the distance between the bridge 6 and the right hand end of the crest. correspondingly, the maximum length of the string also occurs at this time, and corresponds to the distance between the bridge ill and this point 'of contact.

The mechanism for rotating the rods i3, l4, l5, and i6 is shown to best advantage in Figs. 3, 4, and 5. This mechanism is quite similar to that described in the said prior patent. It includes the use of racks and pinions for the rotation of the rods.

Since this mechanism is similar for each of the rods, but one of them will be described in detail: that which is associated with the rod i4. The hollow extension of this rod carries a pinion 37. This pinion is in mesh with a rack 38. Rack 38 is mounted upon the top surface of a manually operable key member 39. This key member is slidable transversely of the axis of rotation of the pinion 31. To provide a guide for the key 39, side walls 46 and 4! are shown as extending upwardly from thebottom plate (see also Figs. 10 and 11). Each of these walls is provided with a series of deep slots, such as 42 and 43, adjacent the bottom of the walls, to permit the passage ofthe racks 38. Furthermore, from the sides of these slots extend transverse narrow slots in which the edges of the respective keys are slidably mounted. In this manner, relatively widely spaced guides are provided; and there is a corresponding ensurance against any of the keys binding in the guides.

For facilitating manipulation of the keys, they are each provided with an upper extension 44 joined to the key 39, as by the aid of the intermediate portion 45 (Fig. 5). These portions 45 of each of the key members provide places where finger pressure may be applied to urge the racks 38 inwardly, or toward the right, as viewed in Fig. 5.

Limits are provided for the movement of the keys 39. For this purpose, each of the keys is provided with a pair of spaced stops 46 and 41 (Figs. 5 and 10). Co-operating with all of the stops on all of the keys is a transverse stop bar 48. This bar isaccommodated in a support 49. This support 49 is shown as extending along the right hand edge of the plate 36. This support 49 has a slot for the accommodation of the stop 48, as shown most clearly in Fig. 5. In order to hold the stop 48 against withdrawal upwardly from the slot, the slot is provided with a series of covering portions 59 (Figs. 10 and 11). The spaces between these portions 59 correspond to the spacing of the racks 38. r a

When the keys 39 are released, spring pressure is utilized to urge the keys to the extreme left hand position, as illustrated in Fig. 5. For this purpose, a torsion spring is placed inside each of the hollow extensions 24, 25, 26, and 27. The torsion spring 5i, associated with the hollow extension 25, is shown in Figs. 3 and 4. The description of the manner in which this spring is accommodated and supported serves as a description for the spring supports in all of the extensions 24, 25, 26, and 21.

The right hand end of the spring 5| is telescoped over the cylindrical member 52 and is permanently anchored thereto. This cylindrical member 52 is formed integrally with a block 53 fastened within the rod L4, as by the screw 54. The left hand end of the spring 5| is similarly anchored to a cylindrical member 55 that is formed integrally with a block 56 disposed in the extension 25. This block 56 has a cylindrical member 51 extending into the hollow bearing member 28, A pin 58 extends radially from the member 51 and is accommodated in a sloping slot 59 of the bearing member 28. The torsion of the spring is in such direction that the pin 58 is urged into the bottom of the slot 59.

Furthermore, the torsion provides a force constantly urging the corresponding bar I3, I4, I5, or I5 to rotate in a clockwise direction, as viewed in Fig. 5; that is, in a direction to move the keys 39 outwardly. Adjustment of the torsional force Of the spring is readily accomplished by angular adjustment of the bearing member 28. This angular adjustment is facilitated by the aid of a screw driver blade, or the like, co-operating with the slots 36 formed in the head 32 of the bearing member, all as explained hereinbefore. During adjustment the set screws are, of course, released.

From the foregoing it is seen that the bearing member 28 serves two functions: one, to support the rod I4 so that it may rotate, and another, to provide a convenient adjustment of the spring torsion.

In order to facilitate adjustment of the angular position of each of the rods I3, I4, I5, and I6, fret marks may be provided. Such fret marks are shown most clearly in Fig. 3. They constitute a set of marks BI disposed on one side of the crest, and a corresponding set of marks 62' on the other side of the crest. Each set is intended to be used respectively with the two sections of the string being stopped; set M indicates the tone produced by the string section between the crest and bridge 6; and set 62 indicates the tone produced by the string section extending between the crest and bridge I0.

Provisions are made for covering the key mechanisms, and in such manner that the cover may be lifted when desired. Accordingly, a sheet metal cover 63 (Figs. 1, 2, 4, 5, and 10) is shown as extending over the left hand ends of the rotatable rods I3, I4, I5, and I6. This cover is provided with a pair of bearing ears 64 (see particularly Fig. 3). One of the cars 64, as shown most clearly in Fig. 3, co-operates with a bearing pin 85 formed on the end of a bearing screw 66. This bearing screw 66 is supported adjacent the top of a bar 61 that is fastened to the top of the walls and 4|. The other car 64 similarly cooperates with a bearing pin supported adjacent the top of the wall 29.

The vibrations of the string structures 2, 3, 4, and 5 are caused to affect an electric pick-up circuit. The pick-up devices are indicated in Figs. 1 and 2. They may comprise magnetic projections 58 and 69, respectively adjacent the bridge 6 and the bridge I0 underneath the string structures, which are purposely made from magnetic material, These magnetic projections cooperate with the strings, and form elements of an electric pick-up device, such as III or II, disposed in appropriate cavities in the body I. These two sets of pick-up devices 68 and 69 cooperate respectively with the sections of the strings defined by the points of contact of the crests on rod I3, I4, I5, or IS.

The two pick-up devices III and II may be connected in parallel to a common output circuit, as indicated in Fig. 13. Thus, the pick-up device I0 is shOWn as connected by the aid of leads I2 and I3 to the output leads I4 and I5. The pickup device II is similarly connected, as by a lead I6, to the output lead I4. The other output lead is connected to the opposite terminal of pickup device II through a conducting bar I! and an adjustable resistance I8. This adjustable resistance I8 is shown as disposed in a cavity I9 (Fig. 2) in the body I. Resistance I8 may be controlled by the aid of a rotary adjusting member that lies substantially flush with the upper surface of body I. This resistance I8 is adjusted in such manner as to ensure that there is no undesired circulation of energy between the two pick-up devices, and so that they may properly function in parallel.

In order that the instrument be capable of performing most effectively, it is desirable that both the tone and volume of the produced sound be under control of the player. This can be done electrically in many Ways; but, in the present instance, the control of tone and volume is greatly simplified.

The stationary parts of the control device are shown as supported upon an insulation panel 8| (Figs. 6 and 12). This insulation panel is appropriately attached, as by screws 82, to the bottom of a cavity 83 formed in the body I.

The tone and volume control includes elements of high impedance that are variable and that may be connected in parallel to the pick-up device I0 and I I. In the present instance these impedance devices are in the form of molded or ceramic resistances fastened to the top of the panel 8I and indicated by reference characters 8! and 88. The exposed upper surfaces of these resistances are intended to be contacted by sliding spring fingers 89 and 95. The structure and the supports for these fingers will be described hereinafter.

Resistance 8? is associated with the tone control, and resistance 88 is associated with the volume control. As indicated most clearly in the diagram, Fig. 13, these molded resistances are so constructed that equal increments of movement along the length of the resistance correspond to unequal resistances. Thus, in both cases, for equal increments of movement of the contacts 89 and 99 from the extreme limiting left hand end of each of the resistances and toward the right hand end, the increments of resistance decrease to the central taps SI and 92; and from then on the increments of resistance increase for equal increments of movement of the contacts.

The contacts 89, 96, are formed respectively integrally with contacts 86 and (Fig. 6) that bear upon the bus bars 84 and II respectively. Thus, these contacts form the ends of the legs of a pair of U-shaped structures 99 and IE0, made from resilient metal.

The volume and tone controls can be described effectively in connection with Fig. 13. When the contacts 85, 85, 39, and are at the extreme left hand position With respect to the bars I! and 84 and the resistances 8! and 88, then the contact finger 89 is in contact with the extreme left hand portion of the tone control resistance 81. The contact point 9i; is out of contact with the volume control resistance 88, since this resistance does not extend so far toward the left as resistance 81. In this position, a high resistance is in series with a tone control filter 94, which is placed in parallel across the output leads I4 and I5. This parallel circuit may be traced as follows: From lead I4, connection 93, bar 84, contacts 86 and 89,

7 resistance 81, central tap 9i, through filter 94, and connection 95 to the lead'lE.

Movement of the contact structure 99-I00 toward the right'gradually reduces the resistance in this tone control circuit. This resistance reaches a minimum'when the contact point 89 is at center tap 9|. From that stage on, further movement of contact 89 toward the right causes resistance to be inserted in the tone control circuit at an increasing rate, This resistance b comes infinite as the contact 89 is moved beyond the right hand end of resistance 3?.

The volume control is efiected by aid of resistance 88 that is simply connected in parallel to the pick-ups 'Ifl'and II. In the first movement of the contacts 85, 86, 89, and 9!! from the extremeleft hand position to a position corresponding to the center tap SI of the tone control, the volume control resistance 88 is disconnected. However, in the movement of the contacts from a position corresponding to the center tap 9| to a position corresponding to the center tap 92 of resistance 88, both the tone control resistance 81 and the volume control resistance 88 are in active engagement with their respective contacts 89 and 90. The parallel circuit of the volume control may be traced as follows: from lead 74, connection 96, center tap 92, contact point 90, connection 91, contact. 85, bar TI, to the output lead I5.

As the contact at moves from left to right, as viewed in Fig. 13, increments of resistance in the "volume control are cut out of the circuit. These increments, for uniform movement of the contacts, decrease as the center tap 92 is approached. When contact 90 is in a position corresponding to this center tap, the resistance is at a minimum and the volume is greatly reduced. Continued movement of the contacts toward the right causes an increase in the resistance in the volume control by ever increasing increments, corresponding to a gradual increase in volume.

During that interval of movement between center taps SI and 92, the tone and volume controls are simultaneously active. Movement of the contacts 85, 85, 39, and 99 between the left hand limit of motion and the center tap 9| corresponds to control of tone alone; and, similarly, movement of the contacts to the right away from center tap 92 corresponds to control of volume alone- Continuous movement in one direction of the contacts 85, 86, 89, and 9e thus produces three phases of operation: one, in which only one of the control impedances is varied; two, when both impedances are varied; and three, when the other of the two impedances alone is varied.

Contacts 85, 8t, 89, and 96 may beconveniently supported by the aid of the arm 98 (Figs. 4, 6, and 12) This arm 98 carries the U-shaped members 99 and Hill, the arms of which terminate in the contacts 859fi and 8689' respectively. These conductors 99 and Its are insulated from the arm 98, as indicated diagrammatically in Fig.

12. This may be accomplished by the provision of insulation layers IilI, ItZ, and bushings N13.

The arm 93 forms one arm of a lever I05 which is rotatable on an axis I86 (Figs. 4, 5, and 6). For this purpose the lever "I5 is provided with a downwardly extending cylindrical projection I06 that is journalled in a bearing sleeve I07 supported in the bottom of the body cavity I08. This bearing sleeve It" is shown as provided with a relatively wide flange I09, by theaid of which it may be secured to the body I. The lower end 1mg of the projection IUBis provided with a'squared end for the accommodation of the manually operable lever III) that is located at the bottom of the body I. This. lever is provided with a finger receiving portion, or saddle, III (Figs. 2, 4, and 9) by the aid of which a player can manipulate the lever I05 from the lower side of the body I.

Angular movement of lever I05 can also be accomplished from above the body I by the aid of the upwardly extending projection II 2 fastened to the lever I05 (Figs. 2, 4, and 5). This projec tion II2 likewise terminates in a finger receiving portion H3 capable of being manipulated, as by the thumb of the player. The portion IIZ, as shown most clearly in Figs. 3 and 6, is permitted freedom of motion by the aid of a recess defined. by the arcuate wall I I i in the body I. The body I may also be provided with a longitudinal recess, such as recess H5 (Figs. 5 and 6) for the accommodation of the leads I I 5 extending to the pick up device 'II.

In playing theinstru'ment, it may be desirable at times to damp the vibrations in those sections of the string structures that are not to be vibrated. For this purpose felt damper pads III and H3 are provided. These damper pads are shown to best advantage in Figs. 1, 2, 3, 4, and 7. Theyiare arranged transversely of the strings, and extend through appropriate slots in the metal plates H9 and I28 respectively.

Damper pad I58 is shown as fastened into a U shaped trough-like member IZI (Fig. 7). This support, in turn, is carried by the arms I22 and I23 (see also Fig. 8). These arms, in turn, are shown as attached to a bar I2 3 that is pivotally mounted in the ears I25 projecting below the plate 126. Rocking of the bar I24 is accomplished by the aid of the arms I28 and I21, depending from the bar I2 3. The linkage whereby these arms I26 and I2? are operated will be de-- scribed hereinafter.

Damper pad III is similarly supported by the aid of the plate H9. It, too, is provided with an operating arm I29.

To move arms I23 and I 29 in unison, their lower extremesare joined by link I30 (Figs. 3, 5, 6, 7, audit); This link extends through an appropriate recess IEI extending longitudinally of the body I.

The manner in which the link I39 is connected to the arms I26 and I2? is shown most clearly in Figs. 6, '7, and 8. Arm I26 has a hub I32. Since the structures for both dampers are similar, only that associated with the left hand hub I32'need be described. A bar I33 is threaded into hub' I32. This bar I33 is pivotally supported in the clevis ltd joined to the link I38, the ears of which are disposed on the opposite sides of the hub I32. similarly, the lower end of arm I27 is provided with an aperture for the passage of the bar I33.

The leit'hand end of bar I33 is spaced from the arm I27, as by a spacer sleeve I35. This sleeve is disposed between the arm 52'! and an arm I36 that extends through a slot It? in the bottom of the body I. The bar I33 is provided with a slotted head I38 to facilitate assembly. The arm I33, as will be explained hereinafter, is provided for manipulation of the dampers III, I is from below the body I.

Manual movement of link I313 is accomplished by the hand or finger of the player, accommodated in a saddle-like structure I39 (Figs. 1, 2, and 7). This structure I39 is shown as extend- 7 mg above the body I, and carried by the support I40, shown as integrally formed with the link I30. Furthermore, movement toward the right, as viewed'in Fig. 7, willcause damper IIS to be active and-damper II Ito bereleased. Movement toward thelleft causesdamper II? to be active and damper lis to-b'e-released. In the intermediateposition illustrated; neither damper is active.

Provisions are made for operating the dampers from below the body I. It is for this purpose that arm I36 (Figs. 4, 5, 8, and 9) is utilized. In addition, another arm I4I, spaced from arm I36, is also joined to the bar I33. It extends downwardly through a slot I42. The lower ends of these bars I36 and MI are rigidly fastened to an operating plate I43 of general triangular configuration. This operating plate I 43 is dis posed at the bottom side of the instrument for ready manual operation by the player. For facilitating such operation, a proiection I49 (Fig. 2) is formed on the plate I43. By movement of plate I43 toward the left of the body I, the arms I36 and MI are caused to operate the arms I28 and I21, and thereby the damping devices are likewise operated. Since the arms I36 and I4I are moved angularly about the axis of bar I33, the plate I43 is permitted to tilt during movement of the plate.

For this purpose, the plate I43 is supported at its right hand end by the aid of an elongated socket I44 carried integrally of the plate at its right hand portion. This socket provides a passageway I45 into which is accommodated the ball end I46 of a stationary arm I41 (Fig. 4) and is attached to the bottom of the body I, as by the aid of the plate I48. The ball I45 permits limited universal movement of plate I43. The plate is retained in proper position at its forward, or left hand, end, since it is permanently attached to the lower ends of arms I35 and I II.

The damper operating arms I22 and I23 can be urged by the player strongly enough to lift the strings from the crests on the rods I4, I5, IS, and II. of the crested rods while the strings are out of contact with the rods. Accordingly. it is possible to adjust the free vibrating lengths abruptly.

The inventor claims:

1. In a musical instrument, a string, means for tensioning said string between two fixed points, mechanism for stopping the string along points extending between an intermediate portion of the str ng and one of the fixed points, and means for rendering the vibrations of both portions of the string, as defined by the stopping means, optionally effective to produce sound.

2. In a musical instrument, a string, means for tensioning said string between two fixed points, a rotatable rod beneath the string and provided with means to stop the string along any of a series of points that extend between an intermediate portion of the string and one of the fixed points, and in accordance with the angular adjustment of the rod, and means for rendering the vibrations of both portions of the string defined by the stopping means, to be optionally effective to produce sound.

3. In a musical instrument, a tensioned string, a rotatable rod having an axis substantially parallel with the string, said rod having provisions for determining the free length of vibration of the string, and in accordance with the angular position of the rod, said rod having a hollow extension, a torsion spring in said ex- In this way, it is possible to rotate any iii) tension for u-rgingthe rod torotate in one direction, means for attaching oneend-ofthe spring in the extension, means for anchoring the other end of the spring, and means for moving the rod angularlyagai-nst the torsion ot-saidspring, including a member mountedexteriorly on saidhol- 10w ext n i n.

4. In a musical instrument, a tensioned string, a rotatable rod having an axis substantially parallel with the string, said rod having provisions for determining the free length of vibration of the string, and in accordance with the angular position of the rod, said rod having a hollow extension, a torsion spring in said extension for urging the rod to rotate in one direction, means for attaching one end of the spring in the extension, means forming a bearing for the rod and co-operating with the interior surface of the extension, means joining the other end of the spring with the bearing forming means, and means for adjusting the force of said spring by angular adjustment of said bearing forming means.

5. In a musical instrument, a tensioned string, means for determining the free vibrating length of the string, a vibration damper arranged laterally of the string, and means for moving said damper to active or inactive position.

6. In a musical instrument, a string, means for tensioning said string between. two fixed points, string contacting means operating intermediate said points to provide a pair of free vibrating string sections, a pair of vibration damper means arranged respectively laterally of the string sections, and a common means for operating said dampers.

7. In a musical instrument, a string, means for tensioning said string between two fixed points, string contacting means operating intermediate said points to provide a pair of free vibrating string sections, a pair of vibration damper means arranged respectively laterally of the string sections, and a common means for operating said dampers in such manner that, as one moves away from the associated section, the other damper approaches its corresponding section.

8. In a musical instrument, a body, one or more strings supported on the body, means for tensioning said strings between two fixed points, means for adjusting the free vibrating lengths of the strings, a vibration damper arranged laterally of the strings, and means for operating said damper from either the top or bottom of the body.

9. In a musical instrument, one or more strings, means for tensioning said strings between two fixed points, a rotatable rod associated with each string and having an axis substantially parallel to the string, as well as a helical-like crest for forming two vibrating string sections, defined by said fixed points and the crest, and means for angularly adjusting the rods, each of said crests having a pair of sets of fret marks respectively on each side of the crest, the sets of marks being respectively related to the two fixed points for indicating the tones corresponding to the string sections.

10. In a stringed musical instrument, one or more tensioned strings, means including a movable crest adapted to contact the string, for adjusting the free length of the string by small increments, a damper extending across the string, and means for so operating the damper as to lift the string off the crest.

JOHN W. MCBRIDE.

(References on following page) 1 1 REFERENCES CITED Number r 551,254 The following re ferenges are of record in the 575 707 file of thls patent. V v r 9 U I 1604196 UNITED STATES PATENTS 5 2,316,799 umb'r Name Date 2,316,800 N 6 2,320,837

534,175 Roos 1 b. 1 2, 1895 12 Name Date Brand Dec. 10, 1895 Dexter Jan. 26, 1897 Potter Oct. 26, 1926 McBride 1 Apr. 20, 1943 McBride Apr. 20, 1943 Turner et a1. June 1, 1943 

